Process of preparing dry powder from emulsions and solutions



Patented June 16, 1936 PROCESS OF PREPARING DRY POWDER FROM EM'ULSIONS AND SOLUTIONS Johan Marie Visser, Nijmegen. Netherlands No Drawing. Application November 25, 1932,

Serial No. 844,401. In the Netherlands November 27, 1931 7 Claims. (Cl. -99203) In many cases it is necessary when drying By spraying the liquid or emulsion which must be emulsions and solutions to powder to keep the dried on a finely powdered solid substance which temperature at which the drying. takes place is stirred and heated a formation of powder can as low as possible in order to prevent the chembe obtained by the quick evaporation, whereby 6 ice] constituents of the substance from being the danger of decomposition of the substance attacked and thus the quality of the dry sub-- which is evaporated to powder is very trifling. stance lessened. This does not apply of course to According to the invention it is also possible to all those cases whereby the dissolved substance is take a finely powdered solid substance, which is insensitive to more or less high temperatures. heated and stirred and on which the liquid or 10 In preparing dry substances from solutions and emulsion, which is to be dried, is sprayed, a 10 emulsions, which are of organic origin, the tempowder which has been obtained before from the perature plays a very great part and this invenliquid or emulsion and thus to obtain immedition has for its object to render it possible to ately a, powder as final product which is not prepare dry substances out of such solutions and mixed with the strange substance. By working in emulsions without the chemical composition of an air-rarefied space in which the evaporation 15 the matter to be dried, being altered. of the liquid occurs, the temperature is lowered,

In regard to milk, till now, no process is whereby the risk of decomposition is furknown, whereby a chemically unchanged milkther diminished. By altering the vacuum it is powder is obtained. In judging this it is insufiipossible to let the evaporation take place at such cient to pay attention only to the solubility of a temperature as is necessary to prevent any de- 20 the obtained powder, as there exist also conver composition of the dry substance. sion products of the milk which are also soluble. The spraying of milk in an air-rarefied space is It has also appeared that the milk fat is altered in itself known, see British Patent 112,965. chemically by oxidation, whereby the powder in With the method according to this specification the long run obtains an unfavourable odor and no high vacuum is, however, obtainable whereas 25 taste. Fm'thermore the vitamin-A is destroyed in the ai a efied Space no powd is ou htby oxidation. Also it is proposed in the British Patent 155,927 With the known process of Hat'maker which to dry milk and such like substances as quickly is worked with relatively high temperature and and as intensively as possible by making the 80 without rarefaction of the air a milk powder is liquid surface as large as possible avoiding the obtained, which is alreadly partly converted, in use of a stream of drying gas. which the fat bulbs present are not emulgated In the Dutch Patent 12,839 a process is dewhen dissolving the powder, scribed whereby liquids act upon solid substances In the process of Krause a very great quantity spread out in powder form in the upper part of air must be heated and this, in view of the of a tower which action takes place in the form 35 bad heat-transmissions of air is always very ofaspraying haze and which is supplied to the upcostly whereas the fat is converted by oindation per part of the tower by means of a stream of-air by the great quantity of oxygen which is present in from beneath to above through the tower the the air, so that the powder obtains after a short fall of the particles beingdelayed as much as time an unfavourable odor and taste. 1 possible. In this process the liquid is exposed The process according to this invention conas long as possible to a stream of air in order sists in taking the liquid or emulsion which must to lengthen the period of reaction. Therefore be dried and bringing it in finely divided condiin those cases where the liquid which must be tion into an air-rarefied space in contact with a treated contains substances, the chemical compoheated, finely powdered solid matter which at sition of which alters easily under the action the beginning of the process is already present of the air, this process cannot therefore be apon the bottom of the spraying space and which plied in case the aim is to dry such a liquid withbinds the fluid particles by absorption or adout alteration of the chemical constituents. Ansorption and by means of its great surface proother important difference with the process acmotes the quick evaporation of the liquid parcording to the invention consists herein that there ticles, whereas the vapor which forms is continis a heated finely powdered solid substance presually sucked ofl. ent in the beginning.

In contrast with the sprayers of Krause, at Two processes are also known (see C-Knoch the beginning of this process powdery material Handbuch der neuzeitlichen Milchverwertung) is present on the bottom of the spraying space. for drying liquids whichit is truework with. 55

vacuum but differ principally from the process according to the invention. These are the vacuum-spray-drying-drums manufactured by the Chemcal and Vacuum-Machinery Co. Inc., whereby the liquid in a space with more or less vacuum is sprayed against a heated rotating cylinder and the obtained mass is continually scraped or! and the Exsikkator of Ekenberg, whereby a heated drum rotating in a space kept under more or less vacuum is dipped in the liquid which is to be dried and the mass after drying is also scraped ofl.

The great principal difference with the process according to the invention consists herein that it is expedient for a quick evaporation besides the spraying use is made of a finely divided heated dry substance which is present in the apparatus beforehand.

The use of the process according to the invention for making milkpowder from fresh milk is of very great importance. The heating of the absorbing substance (either a strange substance or milkpowder originating from a previous charge) can take place in a known manner in a cask with double bottom through which warm water is led, whereas a stirrer provides for the desired division and by means of a vacuum device thedesired degree of rarefaction of the air is obtained. This rarefaction of. the air not only has the advantage that the evaporation temperature is lowered but has, by the application of the. process on the manufacture of milkpowder, as second advantage that the powder comes into contact with a minimum of air so that the danger of oxidation is prevented to a high degree. With this process it is therefore possible to obtain pure milkpowder, in which thevitamin-A has remained untouched.

The used cask with double bottom can have a total content of 1m with an effective content of about half.

For an absorbing substance 25 kg. of very fine powdered sugar can be used which on account of the fine division has a very large surface. This powdered sugar is kept in violent movement by a stirrer.

In the double bottom warm water or steam circulates with such a speed and in such quantity and at such temperature that a good transmission of heat takes place.

In case the milk is pasteurized and in that case immediately after the pasteurization and therefore at a high temperature: (60 to 70 C.) the milk is sprayed in finely divided condition into the cask where a vacuum of 700 mm. mercury column, is maintained which corresponds with a boiling temperature of water of. 41 to 42 C.

As long as the milk still contains all the water a high temperature can be applied without producing the danger that the constituents are converted. However, as soon as the water is evaporated a low temperature must be provided for and this may not rise above the temperature corresponding with the rarefaction of the air. In order to obtain a final product with 30% added sugar, 48 kg. milkpowder must be present in the mixture and to this add about 400 1. fresh full milk to be atomized. The whole process by good transmission of heat takes place in about one hour.

For obtaining the sugar product 20 kg. powdered sugar must be brought in the spraying space.

After having obtained a certain mixture of sugar-milkpowder it is, however, also possible to use a part thereof for the next charge etc. till if desired the sugar percentage has come practicallyto zero.

In case the total obtained quantity must be a 6 pure milk product without admixture of sugar or the like, a commercially obtainable milk powder can be used as solid substance.

The pure milk product finally obtained can always be used for a next charge.

It is evident that for the preparation of milkpowder according to the invention sterilized milk can be used as well as fresh and pasteurized milk.

In applying the process according to the invention a limited and cheap device will do as no high temperature and therefore no high pressure steam apparatus is required whereas for the vacuum use can be made of a connection with the local electrical network. 20 It is evident also thata combination of another solid substance with another liquid, solution or emulsion which is atomized can be prepared with the process of the invention.

The preparation of a cheap vitamin-product of 25 cheap primordial substances (natural products) is contemplated, of which small quantities which are added to margarine give it a suflicient content of vitamins.

In case primordial substances are worked up which will certainly contain all the vitamins A, B, C and D, then the margarineprovided with this vitamin product will be of greater value than summer butter as it will contain a greater quantity of vitamin c and most certainly it willhave 35 a higher content of all vitamins than winter butter.

Besides an addition to margarine of vitaminproduct manufactured in the above way, this method canalso be used for making very cheap 40 tablets which also will certainly contain all vitamins A to D and indeed in such quantity that by v consumption of one tablet each day children can be given all the vitamins they require in order to protect them from all illnesses caused by lack of vitamins especially in the season when fruit or fresh vegetables are not easily obtainable.

Sundry modifications are possible within the scope of the invention and more particularly for instance to use a suspension or an emulsion or a combination of both instead of a solution.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:-

1. A process of preparing dry powder from substances in solution which consists in first depositing a heated and finely divided solid substance on the bottom of an air-rarefied heated chamber, then spraying said solution in a finely divided state into said chamber over said solid substance 60 under constant stirring and finally and continuously removing the arising vapors.

2. A process in accordance with claim 1 in which said heated and powdered solid substance consists of powder previously evaporated from 65 such solution.

3. A process of drying substances in solution which are sensitive to oxygen and temperature changes, which process consists in depositing an absorbent solid substance on the bottom of a 70 heated .vacuum chamber, and spraying said solution into said chamber over said solid substance during constant stirring.

4. A process in accordance with claim 3 in which said absorbent substance consists of a 75 6. A process of preparing milk powder from 10 fresh milk, which consists in first depositing fine powdered sugar on the bottom of an air-rarefied heated chamber, then spraying the fresh milk in a finely divided state into said chamber over said sugar deposit under constant stirring and continuously removing the arising vapors.

'7. A process according to claim 6, in which the proportion of the ingredients is from 5 to 12 kg. of sugar to 100 liters fresh milk.

JOHAN MARIE VISSER. 

